Tymoshenko's wife was sentenced in October to seven years in prison for abuse of office in what the US and the European Union denounced as a politically-motivated trial.

The Czech Republic has a policy of supporting opposition in countries that have patchy human rights records, a legacy of Vaclav Havel, the late president.

Last year, the Czech Republic granted asylum to Bohdan Danylyshyn, a former economy minister in Tymoshenko's cabinet, who is wanted in Ukraine for suspected abuse of office.

Ukraine expelled two Czech diplomats as a result, with the Czechs retaliating later in the year, straining relations.

Oleksander Tymoshenko is part owner of a business registered in the Czech Republic.

'Orange Revolution'

Yulia Tymoshenko's case has seriously affected relations between President Viktor Yanukovich's government and the West.

The EU, which had planned initial agreements on political association and free trade with Ukraine at a summit in December, put off the signing and cited Tymoshenko's case as an example of selective justice in the former Soviet republic.

Tymoshenko served as prime minister after helping to lead the 2004 "Orange Revolution" protests, which overturned an election victory for Yanukovich in his first bid for the presidency and which, for a while, cast him adrift politically.

She has denied abusing her powers when forcing through a 2009 gas deal with Russia as prime minister.

The 51-year-old has recently been moved to a prison cell under 24-hour camera surveillance.